First, let me welcome you to the forum, and to the wonderful world of Krags!  For some of us, they're a way of life!  Be careful... Krags tend to multiply when you're not looking.

Let's start with the basics.  Remington ammo is seasonal, but right now it's the season.  Usually, you can find it at places like Cabela's, and some mom & pop stores.  You can also occasionally find it on sites like Midway, Graf & Sons, Cheaper Than Dirt, etc.  If you plan on shooting often, then reloading is the way to go!  Bullets, primers and powder are readily available.  Brass is another story, so if you do get ammo, SAVE YOUR BRASS!  Currently, Graf & Sons just recently started selling brass under their label, although they're now sold out... but I expect they'll have more based on how much they sold and how quickly it sold out. 

Ok, let's talk about your Krag.  I'm sure that you'll find dozens of people here that would love to see some pictures.  Not to scare you, but if it's an 1898, there were only 5000 made and it's absolutely serial number specific!  Has the Krag been sporterized for hunting?  Pictures and the serial number will tell the tale.  There are also a few things you can look for:  What is the barrel length?  It should be exactly 22 inches from the muzzle to the closed bolt face.  Also, is the front sight banded?  The rear sight is also carbine specific, and should be marked as such with a "C".  If you look at the photo page on this site, there are pictures which should help you identify the  rear sight:    (You need to Login

Hope this all helps